When to plant Dahlias in Perth

Dahlia pinnata

Dahlia
Dahlia · Dahlia pinnata

Show-stopping tuberous perennials that provide a spectacular display of colour from mid-summer right up until the first frosts. Ranging from enormous 'dinner plate' blooms to intricate pompoms and open-centred varieties that bees adore, they are a staple of the late summer UK garden.

100 cm · Full Sun · High Water

Add to garden

Calibrated to Perth · average last frost around 9 May

Sow indoors March, plant out May to June. Typical frost risk October to May.
ActivityJanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember
Sow indoorsNoNoYesNoNoNoNoNoNoNoNoNo
Plant outNoNoNoNoYesYesNoNoNoNoNoNo

Growing guide

What to do through the growing season

Growing guide for

Change the guide to see different planting timelines and tips.

Growing dahlias from seed for bedding varieties, sown indoors in early spring for summer flowers.

  1. 01

    Sow Seeds Indoors

    14 Mar to 28 Mar

    Sow thinly on moist seed compost from 14th March - 28th March. Cover lightly and keep at in the light. They take 7–14 days to come up.

  2. 02

    Prick Out Seedlings

    28 Mar to 18 Apr Dates as each sowing reaches this stage

    Once they have true leaves, pot them on from 28th March - 18th April. Hold the leaves, not the stem, and keep them in good light.

  3. 03

    Harden Off Plants

    9 May to 23 May

    Harden off from 9th May - 23rd May over 10–14 days. Give them a little more outdoor time each day, and keep them off frost and strong wind.

  4. 04

    Plant Outdoors

    23 May to 6 Jun

    Plant out after frost from 23rd May - 6th June, in beds or pots. Space cm apart in full sun and water in. Use a cloche if a cold night is coming.

  5. 05

    Pinch for Bushiness

    6 Jun to 27 Jun Dates as each sowing reaches this stage

    From 6th June - 27th June, pinch the growing tip when plants are so they make more shoots and flowers.

  6. 06

    Water and Feed

    13 Jun to 25 Sept Dates as each sowing reaches this stage Optional · repeat every 2 weeks

    Keep the soil moist. Feed with a balanced liquid fertiliser every 14 days from 13th June until 25th September.

  7. 07

    Deadhead Flowers

    1 Aug to 2 Oct Dates as each sowing reaches this stage

    Take faded blooms off from 1st August, snipping just above a leaf node so new buds follow.

Companion plants

Tap a plant to see why it works (or doesn't) with Dahlia.

Good companions

Plants to avoid

Why companion planting matters

Companion planting can deter pests, improve pollination, and make better use of space. Some plants confuse pests or attract beneficial insects; others improve soil or offer shade to neighbours that need it.

Suggested varieties

Popular varieties of Dahlia to consider

Bishop of Llandaff

A classic variety with dark foliage and bright red flowers, ideal for borders and excellent for pollinators.

Café au Lait

Popular for weddings, with large, creamy-pink blooms that can reach up to 25cm across.

Happy Days

A compact bedding type, perfect for containers, with prolific flowering in mixed colours.

Dahlia guides by town

See how Dahlia timing shifts in other towns with different frost dates.